TRACE CONTAMINANT REMOVAL BY ACTIVATED CARBON: FACTORS AFFECTING THE COMPETITIVE EFFECTS OF NATURAL ORGANIC MATTER

摘要

Activated carbon is an adsorbent commonly used in drinking water treatment. With its high porosity and consequent high surface area, it is capable of removing a wide range of organic contaminants from water. The effectiveness of activated carbon adsorption is limited by the presence of natural organic matter (NOM) (Najm et al., 1991, Newcombe et al., 2002). Studies have shown that NOM inhibits organic contaminant removal by two major mechanisms (Li et al., 2003a,b, Newcombe et al., 2002): (1.) direct competition, where NOM molecules compete with the contaminants for available adsorption sites and (2.) pore-blockage, where NOM molecules block the entrance to the pores where the contaminants adsorb. The extent and mechanisms of competitive adsorption depend on several factors, most notably the size and carbon surface loading of the NOM molecules and the pore size distribution of adsorbents (Li et al., 2003a,b, Pelekani and Snoeyink, 1999, 2000, 2001). The objective of this study is to advance our understanding of the relationship between the several controlling factors and the mechanism of adsorption inhibition. The competitive effects of Congo Red, a surrogate for NOM, on the removal of atrazine is presented in this manuscript.